Chondroitin Sulfate Hydrogel and Wound Healing in Rabbit Maxillary Sinus Mucosa

Exploring the chondroitin sulfate nanogel's potential in combating nephrotoxicity induced by cisplatin and doxorubicin-An in-vivo study on rats

In this study, we aim to unveil the potential of itaconyl chondroitin sulfate nanogel (ICSNG) in tackling chronic kidney diseases triggered by the administration of CDDP and doxorubicin (Adriamycin, ADR). To that end, the new drug delivery system (ICSNG) was initially prepared, characterized, and loaded with the target drugs. Thereafter, the in-vivo studies were performed using five equally divided groups of 100 male Sprague-Dawley (SD) rats. Biochemical evaluation and immunohistochemistry studies have revealed the renal toxicity and the ameliorative effects of ICSNG on renal function. When ICSNG-based treatments were contrasted with the CDDP and ADR infected groups, they significantly increased paraoxonase-1 (PON-1), superoxide dismutase (SOD), catalase (CAT) and albumin activity and significantly decreased nitric oxide (NO), tumor necrosis factor alpha (TNF-α), creatinine, urea, and cyclooxygenase-2 (COX-2) activity (p < 0.001). The findings of the current study imply that ICSNG may be able to lessen renal inflammation and damage in chronic kidney disorders brought on by the administration of CDDP and ADR. Interestingly, according to the estimated selectivity indices, the ICSNG-encapsulated drugs have demonstrated superior selectivity for cancer MCF-7 cells, over healthy HSF cells, in comparison to the bare drugs.

Role of Nitric Oxide-Releasing Glycosaminoglycans in Wound Healing

Two glycosaminoglycan (GAG) biopolymers, hyaluronic acid (HA) and chondroitin sulfate (CS), were chemically modified via carbodiimide chemistry to facilitate the loading and release of nitric oxide (NO) to develop a multi-action wound healing agent. The resulting NO-releasing GAGs released 0.2-0.9 μmol NO mg^-1 GAG into simulated wound fluid with NO-release half-lives ranging from 20 to 110 min. GAGs containing alkylamines with terminal primary amines and displaying intermediate NO-release kinetics exhibited potent, broad spectrum bactericidal action against three strains each of Pseudomonas aeruginosa and Staphylococcus aureus ranging in antibiotic resistance profile. NO loading of the GAGs was also found to decrease murine TLR4 activation, suggesting that the therapeutic exhibits anti-inflammatory mechanisms. In vitro adhesion and proliferation assays utilizing human dermal fibroblasts and human epidermal keratinocytes displayed differences as a function of the GAG backbone, alkylamine identity, and NO-release properties. In combination with antibacterial properties, the adhesion and proliferation profiles of the GAG derivatives enabled the selection of the most promising wound healing candidates for subsequent in vivo studies. A P. aeruginosa-infected murine wound model revealed the benefits of CS over HA as a pro-wound healing NO donor scaffold, with benefits of accelerated wound closure and decreased bacterial burden attributable to both active NO release and the biopolymer backbone.

Facile engineering of ECM-mimetic injectable dual crosslinking hydrogels with excellent mechanical resilience, tissue adhesion, and biocompatibility

Injectable hydrogels have aroused ever-increasing interest for their cell/biomaterial delivery ability through minimally invasive procedures. Nevertheless, it is still a challenge to simply fabricate natural biopolymer-based injectable hydrogels possessing satisfactory mechanical properties, bioadhesion, and cell delivery ability. Herein, we describe a facile dual crosslinking (DC) strategy for preparing extracellular matrix (ECM) mimetic hydrogels with desirable comprehensive performance. The chondroitin sulfate (CS)- and gelatin (Gel)-based single crosslinked (SC) hydrogels were first developed via reversible borate ester bonds, and further strengthened through the Michael-addition crosslinking reaction or visible-light initiated photopolymerization with thiol-containing polyethylene glycol (PEG) crosslinkers. The dynamic SC hydrogels showed good injectability, pH-sensitive gel-sol transformation, and self-adhesion ability to various biological tissues such as skin, liver, and intervertebral disc. The mechanically tough DC hydrogels displayed tunable stiffness, and resilience to compression load (up to 90% strain) owing to the effective energy dissipation mechanism. The formed DC hydrogels after subcutaneous injection well integrated with surrounding tissues and exhibited fast self-recovery properties. Moreover, the photoencapsulation of human mesenchymal stem cells (hMSCs) within the developed DC hydrogels was achieved and has been proved to be biocompatible, highlighting the great potential of the photopolymerized DC hydrogels in cell delivery and three-dimensional (3D) cell culture. This biomimetic, mechanically resilient, adhesive, and cytocompatible injectable DC hydrogel could serve as a promising candidate for tissue engineering.

Recent advances in PVA-polysaccharide based hydrogels and electrospun nanofibers in biomedical applications: A review

Among several types of carbohydrate polymers blend PVA hydrogel membranes used for biomedical applications in particular wound dressings; electrospun nanofibrous membranes have gained increased interest because of their extraordinary features e.g. huge surface area to volume ratio, high porosity, adequate permeability, excellent wound-exudates absorption capacity, architecture similarity with skin ECM and sustained release-profile over long time. In this study, modern perspectives of synthesized/developed electrospun nanofibrous hydrogel membranes based popular carbohydrate polymers blend PVA which recently have been employed for versatile biomedical applications particularly wound dressings, were discussed intensively and compared in detail with traditional fabricated membranes based films, as well. Clinically relevant and advantages of electrospun nanofibrous membranes were discussed in terms of their biocompatibility and easily fabrication and functionalization in different biomedical applications.

Hyaluronic acid and Chondroitin sulfate from marine and terrestrial sources: Extraction and purification methods

Hyaluronic acid (HA) and chondroitin sulfate (CS) are valuable bioactive polysaccharides that have been highly used in biomedical and pharmaceutical applications. Extensive research was done to ensure their efficient extraction from marine and terrestrial by-products at a high yield and purity, using specific techniques to isolate and purify them. In general, the cartilage is the most common source for CS, while the vitreous humor is main used source of HA. The developed methods were based in general on tissue hydrolysis, removal of proteins and purification of the target biopolymers. They differ in the extraction conditions, enzymes and/or solvents used and the purification technique. This leads to specific purity, molecular weight and sulfation pattern of the isolated HA and CS. This review focuses on the analysis and comparison of different extraction and purification methods developed to isolate these valuable biopolymers from marine and terrestrial animal by-products.

Biopolymer-based biomaterials for accelerated diabetic wound healing: A critical review

Non-healing, chronic wounds place a huge burden on healthcare systems as well as individual patients. These chronic wounds especially diabetic wounds will ultimately lead to compromised mobility, amputation of limbs and even death. Currently, wounds and limb ulcers associated with diabetes remain significant health issues; the associated healthcare cost ultimately leads to the increased clinical burden. The presence of diabetes interrupts a highly coordinated cascade of events in the wound closure process. Advances in the understanding of pathophysiological conditions associated with diabetic wounds lead to the development of drug delivery systems which can enhance wound healing by targeting various phases of the impaired processes. Wound environments typically contain degradative enzymes, along with an elevated pH and demonstrate a physiological cascade involved in the regeneration of tissue, which requires the application of an effective delivery system. This article aims to review the pathophysiological conditions associated with chronic and diabetic wounds. The delivery systems, involved in their treatment are described, highlighting potential biomaterials and polymers for establishing drug delivery systems, specifically for the treatment of diabetic wounds and the promotion of the associated mechanisms involved in advanced wound healing. Emerging approaches and engineered devices for effective wound care are reported. The discussion will give insight into the mechanisms relevant to all stages of wound healing.

Composition of Hyaluronan Affects Wound Healing in the Rabbit Maxillary Sinus

Background

Hyaluronan (HA) is a ubiquitous component of the extracellular matrix. HA and its derivatives have been used in the sinuses to reduce scarring and possibly promote wound healing. However, in recent animal studies, HA esters exhibited inflammatory effects. Mitomycin C (MMC) is another potential antiscarring treatment. This study prospectively evaluated the effects of three different HA constructs on wound healing in the rabbit maxillary sinus: (i) a novel cross-linked HA hydrogel, (ii) the cross-linked HA gel containing covalently bound MMC, and (iii) a commercially available woven HA ester (Merogel).

Methods

Ostia were created with a 4-mm otologic drill in the maxillary sinuses of 15 New Zealand white rabbits with one side randomly chosen for treatment. After 14 or 21 days the size of the maxillary ostia were recorded and the tissue was examined under light microscopy.

Results

Sinuses treated with the novel HA and HA-MMC hydrogels showed an increased ostial diameter compared with untreated controls. Woven HA ester–treated sinuses showed no improvement, with a trend toward a smaller ostium than controls. Histological examination showed that woven HA ester tended to cause increased fibrosis and granulomatous inflammation, and heterophilia was slightly increased in the HA hydrogel-treated sinuses. Blinded observation noted foamy macrophages surrounding the residual woven HA ester in each specimen while no similar reaction was noted near the residual HA or HA-MMC hydrogels.

Conclusion

This study suggests that the degree of ostial narrowing, inflammation, and fibrosis depends on the formulation of the HA used. Minimal, if any, additional benefit is seen with addition of MMC to the HA hydrogel in this pilot study.

Sulfation degree not origin of chondroitin sulfate derivatives modulates keratinocyte response

Chondroitin sulfate (CS) sulfation-dependently binds transforming growth factor-β1 (TGF-β1) and chronic wounds often accompany with epidermal hyperproliferation due to downregulated TGF-β signaling. However, the impact of CS on keratinocytes is unknown. Especially biotechnological-chemical strategies are promising to replace animal-derived CS. Thus, this study aims to evaluate the effects of CS derivatives on the interaction with vascular endothelial growth factor-A (VEGF-A) and on keratinocyte response. Over-sulfated CS (sCS3) interacts stronger with VEGF-A than CS. Furthermore, collagen coatings with CS variants are prepared by in vitro fibrillogenesis. Stability analyses demonstrate that collagen is firmly integrated, while the fibril diameters decrease with increasing sulfation degree. CS variants sulfation-dependently decelerate keratinocyte (HaCaT) migration and proliferation in a scratch assay. HaCaT cultured on sCS3-containing coatings produced increased amounts of solute active TGF-β1 which could be translated into biomaterials able to decrease epidermal hyperproliferation in chronic wounds. Overall, semi-synthetic and natural CS yield to comparable responses.

Effect of a combination of mometasone furoate, levofloxacin, and retinyl palmitate with an in situ gel-forming nasal delivery system on nasal mucosa damage repair in an experimental rabbit model

BACKGROUND

In this study a combination of Mometasone Furoate (MF)+Levofloxacin hemihydrate (LH)+Retinyl palmitate (RP) with an in situ gel-forming delivery system was evaluated at different stages of nasal mucosal damage repair in a rabbit maxillary sinus model.

METHODS

In this study, 28 rabbits were included and assigned randomly to four groups. In all rabbits, a standard ostium was opened in the medial wall of the maxillary sinus by using a drill. Two different subsequently prepared gels with an in situ gel-forming delivery system were used. Of these 14 nasal cavities, combination 1 (active combination) was applied daily to 5, combination 2 (placebo) to 5, while 4 did not receive any pharmaceutical treatment. The diameter of the ostium was measured. Histopathological assessment was performed.

RESULTS

After 2, 3 and 4 weeks, the ostium diameter was significantly wider in the group where gel 1 had been applied compared to both the placebo group and control group. In the group treated with gel 1, after 2, 3 and 4 weeks the presence of superficial cilia was significantly greater, surface epithelium significantly less. In the 4th week, histologic scores for fibroblastic proliferation and vascular proliferation in the group treated with gel 1 were better than in either the control group or the placebo group. With gel 1, chronic inflammation parameters were also significantly lower than in the other groups.

CONCLUSION

The MF+LH+RP mixture with an in situ gel-forming nasal delivery system applied for wound healing after FESS prevents the formation of stenosis and is favorable for proper wound healing.

Smart Carriers and Nanohealers: A Nanomedical Insight on Natural Polymers

Biodegradable polymers are popularly being used in an increasing number of fields in the past few decades. The popularity and favorability of these materials are due to their remarkable properties, enabling a wide range of applications and market requirements to be met. Polymer biodegradable systems are a promising arena of research for targeted and site-specific controlled drug delivery, for developing artificial limbs, 3D porous scaffolds for cellular regeneration or tissue engineering and biosensing applications. Several natural polymers have been identified, blended, functionalized and applied for designing nanoscaffolds and drug carriers as a prerequisite for enumerable bionano technological applications. Apart from these, natural polymers have been well studied and are widely used in material science and industrial fields. The present review explains the prominent features of commonly used natural polymers (polysaccharides and proteins) in various nanomedical applications and reveals the current status of the polymer research in bionanotechnology and science sectors.

The effects of the stem cell on ciliary regeneration of injured rabbit sinonasal epithelium

Defects in mucosal healing after sinonasal surgery cause infection, scar formation causing obstruction, relapse of the disease within a shorter period and revision surgery. The present study aimed to create a functional ciliated epithelium using a stem cell and stem cell sheet of adipose tissue origin and to show such regeneration ultra-structurally on experimentally injured rabbit nasal epithelium. This was an experimental animal study and basic research. A total of 18 white New Zealand rabbits were divided into three groups. The medial wall of the maxillary sinus of the subjects was peeled off bilaterally. No additional procedure was applied to the subjects in Group 1. In Group 2, adipose tissue-derived mesenchymal stem cell was implanted on the wound edges of the subjects. In Group 3, a stem cell sheet of three layers was laid onto the defect area. All subjects were killed after 3 weeks. The presence of the stem cell stained with bromo-deoxyuridine was assessed with a light microscope, whereas cilia density, ciliated orientation and cilia structure were evaluated with a scanning electron microscope. Ciliary densities in Group 2 and Group 3 were statistically superior compared to the control group (p < 0.001, p = 0.007). Cilia morphology in Group 2 and Group 3 was also better than the control group (p < 0.01, p = 0.048). Ciliary orientation in Group 2 was scored highest (p < 0.01). The ratio of BrDu-stained cells was observed to be 27% in Group 3 and 8% in Group 2. Sub-epithelial recovery was observed to be better in Group 3. Adipose tissue-derived mesenchymal stem cell increased the healing of the injured maxillary sinus mucosa of the rabbits in terms of cilia presence, density and morphology regardless of the implementation technique. Level of evidence NA.

Gellan gum based physical hydrogels incorporating highly valuable endogen molecules and associating BMP-2 as bone formation platforms

Physical hydrogels have been designed for a double purpose: as growth factor delivery systems and as scaffolds to support cell colonization and formation of new bone. Specifically, the polysaccharide gellan gum and the ubiquitous endogenous molecules chondroitin, albumin and spermidine have been used as exclusive components of these hydrogels. The mild ionotropic gelation technique was used to preserve the bioactivity of the selected growth factor, rhBMP-2. In vitro tests demonstrated the effective delivery of rhBMP-2 in its bioactive form. In vivo experiments performed in the muscle tissue of Wistar rats provided a proof of concept of the ability of the developed platforms to elicit new bone formation. Furthermore, this biological effect was better than that of a commercial formulation currently used for regenerative purposes, confirming the potential of these hydrogels as new and innovative growth factor delivery platforms and scaffolds for regenerative medicine applications.

Neoproteoglycans in tissue engineering

Proteoglycans, comprised of a core protein to which glycosaminoglycan chains are covalently linked, are an important structural and functional family of macromolecules found in the extracellular matrix. Advances in our understanding of biological interactions have lead to a greater appreciation for the need to design tissue engineering scaffolds that incorporate mimetics of key extracellular matrix components. A variety of synthetic and semisynthetic molecules and polymers have been examined by tissue engineers that serve as structural, chemical and biological replacements for proteoglycans. These proteoglycan mimetics have been referred to as neoproteoglycans and serve as functional and therapeutic replacements for natural proteoglycans that are often unavailable for tissue engineering studies. Although neoproteoglycans have important limitations, such as limited signaling ability and biocompatibility, they have shown promise in replacing the natural activity of proteoglycans through cell and protein binding interactions. This review focuses on the recent in vivo and in vitro tissue engineering applications of three basic types of neoproteoglycan structures, protein-glycosaminoglycan conjugates, nano-glycosaminoglycan composites and polymer-glycosaminoglycan complexes.

Chitosan-hyaluronan/nano chondroitin sulfate ternary composite sponges for medical use

In this work chitosan-hyaluronan composite sponge incorporated with chondroitin sulfate nanoparticle (nCS) was developed. The fabrication of hydrogel was based on simple ionic cross-linking using EDC, followed by lyophilization to obtain the composite sponge. nCS suspension was characterized using DLS and SEM and showed a size range of 100-150 nm. The composite sponges were characterized using SEM, FT-IR and TG-DTA. Porosity, swelling, biodegradation, blood clotting and platelet activation of the prepared sponges were also evaluated. Nanocomposites showed a porosity of 67% and showed enhanced swelling and blood clotting ability. Cytocompatibility and cell adhesion studies of the sponges were done using human dermal fibroblast (HDF) cells and the nanocomposite sponges showed more than 90% viability. Nanocomposite sponges also showed enhanced proliferation of HDF cells within two days of study. These results indicated that this nanocomposite sponges would be a potential candidate for wound dressing.

Injectable and biodegradable hydrogels: gelation, biodegradation and biomedical applications

Injectable hydrogels with biodegradability have in situ formability which in vitro/in vivo allows an effective and homogeneous encapsulation of drugs/cells, and convenient in vivo surgical operation in a minimally invasive way, causing smaller scar size and less pain for patients. Therefore, they have found a variety of biomedical applications, such as drug delivery, cell encapsulation, and tissue engineering. This critical review systematically summarizes the recent progresses on biodegradable and injectable hydrogels fabricated from natural polymers (chitosan, hyaluronic acid, alginates, gelatin, heparin, chondroitin sulfate, etc.) and biodegradable synthetic polymers (polypeptides, polyesters, polyphosphazenes, etc.). The review includes the novel naturally based hydrogels with high potential for biomedical applications developed in the past five years which integrate the excellent biocompatibility of natural polymers/synthetic polypeptides with structural controllability via chemical modification. The gelation and biodegradation which are two key factors to affect the cell fate or drug delivery are highlighted. A brief outlook on the future of injectable and biodegradable hydrogels is also presented (326 references).

Using chondroitin sulfate to improve the viability and biosynthesis of chondrocytes encapsulated in interpenetrating network (IPN) hydrogels of agarose and poly(ethylene glycol) diacrylate

We recently introduced agarose-poly(ethylene glycol) diacrylate (PEGDA) interpenetrating network (IPN) hydrogels to cartilage tissue engineering that were able to encapsulate viable cells and provide a significant improvement in mechanical performance relative to its two constituent hydrogels. The goal of the current study was to develop a novel synthesis protocol to incorporate methacrylated chondroitin sulfate (MCS) into the IPN design hypothesized to improve cell viability and biosynthesis. The IPN was formed by encapsulating porcine chondrocytes in agarose, soaking the construct in a solution of 1:10 MCS:PEGDA, which was then photopolymerized to form a copolymer network as the second network. The IPN with incorporated CS (CS-IPN) (~0.5 wt%) resulted in a 4- to 5-fold increase in the compressive elastic modulus relative to either the PEGDA or agarose gels. After 6 weeks of in vitro culture, more than 50% of the encapsulated chondrocytes remained viable within the CS-modified IPN, in contrast to 35% viability observed in the unmodified. At week 6, the CS-IPN had significantly higher normalized GAG contents (347 ± 34 μg/μg) than unmodified IPNs (158 ± 27 μg/μg, P < 0.05). Overall, the approach of incorporating biopolymers such as CS from native tissue may provide favorable micro-environment and beneficial signals to cells to enhance their overall performance in IPNs.

Synthesis and characterization of dendron cross-linked PEG hydrogels as corneal adhesives

In pursuit of a wound-specific corneal adhesive, hydrogels formed by the reaction of propionaldehyde, butyraldehyde, or 2-oxoethyl succinate-functionalized poly(ethylene glycol) (PEG) with a peptide-based dendritic cross-linker (Lys(3)Cys(4)) were characterized. These macromers react within minutes of mixing to form transparent and elastic hydrogels with in vitro degradation times that range from hours to months based on the type of bonds formed during the cross-linking reaction, either thiazolidine or pseudoproline. The mechanical properties of these materials, determined via parallel plate rheology, were dependent on the polymer concentration, as was the hydrogel adhesive strength, which was determined by lap shear adhesive testing. In addition, these hydrogels were efficacious in closing ex vivo 4.1 mm central corneal lacerations: wounds closed with these hydrogel adhesives were able to withstand intraocular pressure values equivalent to, or in excess of, those obtained by closing the wounds with suturing.

Nasal packing and stenting

Nasal packs are indispensable in ENT practice. This study reviews current indications, effectiveness and risks of nasal packs and stents. In endoscopic surgery, nasal packs should always have smooth surfaces to minimize mucosal damage, improve wound healing and increase patient comfort. Functional endoscopic endonasal sinus surgery allows the use of modern nasal packs, since pressure is no longer required. So called hemostatic/resorbable materials are a first step in this direction. However, they may lead to adhesions and foreign body reactions in mucosal membranes. Simple occlusion is an effective method for creating a moist milieu for improved wound healing and avoiding dryness. Stenting of the frontal sinus is recommended if surgery fails to produce a wide, physiologically shaped drainage path that is sufficiently covered by intact tissue.

Isolation and characterization of chondroitin sulfates from sturgeon (Acipenser sinensis) and their effects on growth of fibroblasts

Chondroitin sulfate (CS) is a glycosaminoglycan that composed of hexosamine (D-galactosamine) and hexuronic acid (D-glucuronic acid) unit arranged in an alternating unbranched sequence. CS is an essential component of the extracellular matrix (ECM) of connective tissue. It is mainly covalently attached to core proteins in the form of proteoglycans so that it exhibits specific interactions with proteins for cell growth, differentiation, division and migration. In this study, CSs were purified from the cartilage and backbone of sturgeon (Acipenser sinensis). To characterize their biochemical properties, we performed disaccharide compositional analysis after chondroitinase ABC digestion, high performance size exclusion chromatography (HPSEC) and (1)H-NMR spectroscopy. We also investigated the effects of CSs on fibroblast proliferation and adhesion to determine whether wound healing was accelerated in vitro and proliferation of different mitogen-activated protein kinases (MAPK) signaling pathways was facilitated. The CS purified from sturgeon cartilage was primarily composed of 4-sulfated CS (88.8%) and sturgeon backbone CS contains more than 60% 6-sulfated CS. The average molecular weights of CSs obtained from sturgeon cartilage and backbone were found to be 8 and 43 kDa, respectively. Our results showed that both CSs are able to increase cell adhesion, induce proliferation and migration on fibroblasts and may accelerate wound healing by inducing MAPK signaling pathways.

Polysaccharide-modified synthetic polymeric biomaterials

This review presents an overview of polysaccharide-conjugated synthetic polymers and their use in tissue-engineered scaffolds and drug-delivery applications. This topic will be divided into four categories: (1) polymeric materials modified with non-mammalian polysaccharides such as alginate, chitin, and dextran; (2) polymers modified with mammalian polysaccharides such as hyaluronan, chondroitin sulfate, and heparin; (3) multi-polysaccharide-derivatized polymer conjugate systems; and (4) polymers containing polysaccharide-mimetic molecules. Each section will discuss relevant conjugation techniques, analysis, and the impact of these materials as micelles, particles, or hydrogels used in in-vitro and in-vivo biomaterial applications.

Specific interactions between human fibroblasts and particular chondroitin sulfate molecules for wound healing

The chondroitin sulfates (CSs) constitute an important group of biomacromolecules in the extracellular matrix. However, limited information is available about their specific biological functions. This study aimed to define the interactions between cells and various types of CS. The effects of CSs on cellular activities and the cell cycle were evaluated using cell culture, RNA interference, real-time polymerase chain reaction, flow cytometry, wound healing and contraction models. The results showed that C-6-S promoted both cell proliferation and adhesion, while C-4-S promoted proliferation but inhibited adhesion. Moreover, knockdown of chondroitin inhibited cell proliferation and migration, as well as arresting cells in the G(2)/M phase. Also, both C-4-S and C-6-S promoted wound closure in a two-dimensional wound model, whereas only C-6-S inhibited wound contraction in a three-dimensional wound model. This study illustrates that the interaction between cells and different CSs are specific and sulfate-group-dependent. These findings provide useful information for better applications of CSs for wound healing.

A Scientific Review of Middle Meatal Packing/stents

Background

Nasal packing usually is placed after endoscopic sinus surgery (ESS) to control hemorrhage, but also may be used to prevent adhesions from forming and promote faster healing of damaged mucosa.

Methods

A literature review was performed to identify all forms of scientifically evaluated absorbable packing for ESS. Only English studies identifiable within the PubMed database were included. Studies were categorized by level of evidence and evaluated for methodological errors.

Results

Thirty-eight studies met the inclusion criteria. There was a diverse range of article evidence and quality.

Conclusion

The most effective hemostatic agent currently available is FloSeal; however, this product causes an increase in adhesion formation. For the purpose of preventing adhesions, resorbable packs appear to have no benefit over either nonresorbables or no packing. If the middle turbinate is unstable at the conclusion of surgery, suturing it to the septum may reduce adhesions. Although mitomycin C, hyaluronic acid, and retinoic acid all have shown potential in these roles, to date, none have shown to be useful in the post-ESS chronic sinusitis human patient.

Structural variations in a single hyaluronan derivative significantly alter wound-healing effects in the rabbit maxillary sinus

BACKGROUND

Biomaterials based on hyaluronan (HA) are currently used after sinus surgery but have not been found to decrease scarring or enhance wound healing. Chemical composition of these modified HA molecules may impact their biological and clinical effects.

OBJECTIVE

To analyze chemical variations of a single crosslinked HA-based hydrogel, chemically modified thiolated HA (CMHA-SX).

METHODS

Four different components of the hydrogel composition were altered, yielding 54 variations. These were subjected to biomechanical testing, and then potential clinically relevant variations were further tested for swelling and degradation characteristics. Using a rabbit maxillary sinus model, the ability of the material variations to stent a neo-ostium was tested. Histologic measures were also assessed. Biomechanical and biological effects were correlated.

RESULTS

Minor compositional changes had profound biomechanical and biological effects. Swelling and rate of enzymatic degradation were closely related. CMHA-SX hydrogels that were the most effective stents in maintaining the neo-ostium also generated the lowest level of acute inflammation, as determined by histology.

CONCLUSIONS

Chemical composition has a significant impact on the clinical potential of modified HA materials. Histocompatibility appears to most significantly affect ostium preservation.

SIGNIFICANCE

Different CMHA-SX hydrogels perform differently in vivo, even when the chemical compositions are quite similar. Objective prospective testing of modified HA materials should precede their clinical use in sinus surgery.

Bone changes after maxillary sinus surgery: an experimental scanning electron microscopy study

AIMS

The purpose of this study was to explore the pathogenic role of bone in sinus surgery, and to determine whether mucosal disease after sinus surgery may be induced by underlying disease within the bone.

MATERIAL AND METHODS

Twenty-five rabbits were divided into five groups. In group one, wide surgical removal of the maxillary sinus mucosa and creation of a nasoantral window were undertaken. In group two, only nasoantral window creation was undertaken. In group three, the mucosa of the anterior maxillary sinus was removed. In group four, a strip of mucosa around the ostium was removed. Group five was used as a control.

RESULTS

After three months, in the groups which had undergone wide surgical removal, the medial sinus walls were observed to be retracted and the inner curtain of the bone disturbed, with alteration of the haversian canal system and osteoclastic bone resorption.

CONCLUSIONS

After radical sinus surgery, electron microscopic changes were observed in the bony walls, similar to those changes seen in osteomyelitis.

Reduced postoperative intra-abdominal adhesions using Carbylan-SX, a semisynthetic glycosaminoglycan hydrogel

OBJECTIVE

To compare the efficacy of crosslinked Carbylan-SX (Carbylan BioSurgery, Inc., Palo Alto, CA) hydrogel films and sprayable gels as physical barriers in reducing postoperative intra-abdominal adhesions in the rat cecum-abdominal wall and rat uterine horn models.

DESIGN

Pre-formed crosslinked Carbylan-SX films and sprayable in situ crosslinkable Carbylan-SX gels were evaluated in rat cecum-abdominal wall and rat uterine horn models and compared with commercially available and clinically used Seprafilm.

SETTING

University animal research facility.

ANIMALS

Female Wistar rats.

INTERVENTION(S)

Abrasions were made with the foot-pedal-operated Flex-shaft (Dremel, Racine, WI) on both the cecum and abdominal wall (each area 10 mm in diameter) in female rats as one model and on both uterine horns (3 x 10 mm) in female rats as the other model. In each of the two adhesion models, four groups were assigned with eight rats in each group: (1) untreated control, (2) treated with Seprafilm (Genzyme Corporation, Cambridge, MA), (3) treated with preformed Carbylan-SX hydrogel films, and (4) treated with sprayable Carbylan-SX gel.

MAIN OUTCOME MEASURE(S)

Extent and severity of postoperative adhesions between the cecum and the abdominal wall in rat cecum-abdominal wall model and between the uterine horns in rat uterine horn model.

RESULT(S)

The Carbylan-SX film and the Carbylan-SX sprayable gel led to fewer adhesions than Seprafilm in both rat adhesion models. Interestingly, a single physical form was not optimal for both models: the Carbylan film was more efficacious in the rat uterine horn model, whereas Carbylan gel gave the best results in the rat cecum-abdominal wall model.

CONCLUSION(S)

Both Carbylan-SX film and gel were efficacious in reducing postoperative intra-abdominal adhesion formation in rat cecum-abdominal wall and uterine horn models.

Cross-Linked Hydrogels for Middle Ear Packing

OBJECTIVE

To develop an ideal supportive packing material for ossiculoplasty, tympanoplasty, or other otologic procedures.

MATERIALS AND METHODS

Several materials, namely, Carbylan-SX (P-C; Sentrx Surgical, Inc., Salt Lake City, UT), Gelfoam (P-GF; Pharmacia & Upjohn, Kalamazoo, MI), and Merogel (P-MG; Medtronics, Inc., Minneapolis, MN), were prepared and then placed into a Hartley guinea pig's (Elm Hill, Chelmsford, MA) middle ear cavities through a large myringotomy incision. The contralateral ear underwent a large myringotomy without packing material being placed. Preoperative and posteroperative auditory brainstem response studies were performed using Intelligent Hearing system software. The animals were examined weekly. Two weeks after packing placement, the animals were killed, and the temporal bones were harvested. Whole temporal bone sectioning was performed to analyze the presence of implant, surrounding inflammation, presence of osteoneogenesis and fibrosis, or adhesions.

RESULTS

All the materials, except the P-MG, were easy to place into the middle ear cavity. The P-MG contains woven strands that are difficult to trim into the small sizes needed for placement. The P-MG group had a smaller average amount of implant present compared with the other groups at 2 weeks. The degree of osteoneogenesis was similar among the P-GF, P-C, and P-MG groups. The P-MG and P-C groups contained the lowest amount of fibrosis between the implant and surrounding middle ear structures.

CONCLUSION

This study demonstrates promising results with P-C as a potential supportive packing material for otologic procedures. P-C compares favorably with P-MG and P-GF in a guinea pig model with respect to ease of placement and amount of fibrosis.

Perioperative care for advanced rhinology procedures

Successful outcomes in rhinologic surgery require careful endoscopic interventions, not only in the operating room, but also in the perioperative setting. In particular, meticulous postoperative care is essential to successful outcomes. This article reviews aspects of wound healing and perioperative care that can optimize surgical patency and clinical outcome.

Cross-linked hyaluronan-coated stents in the prevention of airway stenosis

OBJECTIVE

This project studies the use of airway stents coated with a cross-linked derivative of hyaluronan (HA) in a rabbit airway model of subglottic stenosis (SGS).

STUDY DESIGN AND SETTING

An acute subglottic mucosal injury and airway stent placement design were used in a rabbit model. Thirty-six rabbits were randomized to 6 different study groups. Four groups had the subglottic mucosa denuded at the cricoid, and 2 groups received no injury. Airway stents coated with Carbylan-SX, a cross-linked derivative of HA, and controls were placed for 3 weeks. After sacrifice at 6 weeks, morphometric measurements of subglottic lumen were taken.

RESULTS

In posttraumatic models, no significant differences were seen in airway area measures between groups (P = 0.86). In non-injury groups, a significant difference between Carbylan-SX versus non-HA-derivative-coated stents was seen (P = 0.05).

CONCLUSION

In this model of acute subglottic mucosal injury, the HA-derivative-coated stent did not improve healing. However, in the absence of mucosal injury, the Carbylan-SX film-coated stent yielded significantly larger airway areas compared with a noncoated stent.

SIGNIFICANCE

Stents or endotracheal tubes coated with a cross-linked derivative of HA may prevent stenosis in patients without airway injury but require long-term intubation or laryngotracheal stenting.

Injectable glycosaminoglycan hydrogels for controlled release of human basic fibroblast growth factor

Synthetic hydrogel mimics of the extracellular matrix (ECM) were created by crosslinking a thiol-modified analog of heparin with thiol-modified hyaluronan (HA) or chondroitin sulfate (CS) with poly(ethylene glycol) diacrylate (PEGDA). The covalently bound heparin provided a crosslinkable analog of a heparan sulfate proteoglycan, thus providing a multivalent biomaterial capable of controlled release of basic fibroblast growth factor (bFGF). Hydrogels contained >97% water and formed rapidly in <10min. With as little as 1% (w/w) covalently bound heparin (relative to total glycosaminoglycan content), the rate of release of bFGF in vitro was substantially reduced. Total bFGF released increased with lower percentages of heparin; essentially quantitative release of bFGF was observed from heparin-free hydrogels. Moreover, the hydrogel-released bFGF retained 55% of its biological activity for up to 28 days as determined by a cell proliferation assay. Finally, when these hydrogels were implanted into subcutaneous pockets in Balb/c mice, neovascularization increased dramatically with HA and CS hydrogels that contained both bFGF and crosslinked heparin. In contrast, hydrogels lacking bFGF or crosslinked heparin showed little increase in neovascularization. Thus, covalently linked, heparin-containing glycosaminoglycan hydrogels that can be injected and crosslinked in situ constitute highly promising new materials for controlled release of heparin-binding growth factors in vivo.